Purpose: Little is known about the specific nature of language abilities of autistic adolescents and young adults with language impairment (LI), limiting our knowledge of developmental trajectories and ability to develop efficacious speech/language supports. An important first step is establishing proof of concept of identification of LI in this population, with considerations for feasibility of assessment. This research note describes such a study in a sample of autistic adolescents and young adults with LI. Method: Thirteen autistic adolescents and young adults completed an assessment protocol of age-referenced language and nonverbal cognitive assessments. Assessment took place once per year for 3 years; the first two assessments were conducted in person, and the final was conducted online due to the pandemic. All assessments included measures of overall language and morphosyntax; the third added measures of expressive and receptive vocabulary, verbal working memory, and nonverbal intelligence (NVIQ). Analysis included descriptives and comparison of individual performance with epidemiological criteria for LI. Results: All participants qualified for LI, with overall receptive and expressive language scores persistently in the LI range. Other outcomes were variable. Some participants had nonword repetition and vocabulary abilities within age expectations, and some consistently showed adultlike morphosyntactic performance. NVIQ was variable, with no consistent associations with language outcomes. Discussion: Our findings support the use of the current protocol, as implemented in person or online, to identify LI in autistic adolescents and young adults. This exploratory work is limited by a small sample and missing data. The findings contribute to our understanding of linguistic strengths and variability in the language skills of autistic young adults with LI.